The major objective of this research is to examine the regulation of expression of gene(s) for RNA polymerase I, the enzyme responsible for the synthesis of ribosomal RNA. This study will determine whether the alterations in enzyme activity observed in response to physiological stimuli are due to changes in the number of RNA polymerase I molecules or due to activation of preexisting enzyme. Antibodies to RNA polymerase I will be prepared and levels of RNA polymerase I will be quantitated by radioimmunoassay. Immunological techniques will also be used to ascertain whether RNA polymerase I contains any subunits in common with the other two nuclear RNA polymerases. A radioimmunoassay will be developed to measure individual subunits of RNA polymerase I. The levels of each subunit will be monitored under varying physiological conditions. Such studies will elucidate whether expression of all subunits is coordinately controlled or whether those subunits specific to RNA polymerase I can be regulated independently from the subunits RNA polymerase I has in common with RNA polymerase II and III. The immunological and structural properties of RNA polymerase I from a neoplasm (hepatoma) will be determined and compared to those of enzyme from normal tissue (liver). Such studies will delineate whether unique gene(s) for RNA polymerase I are expressed in neoplasia, a disease state characterized by increased production of ribosomal RNA. Finally, the levels of RNA polymerase I in normal liver and hepatoma will be measured under various dietary and hormonal conditions to determine whether RNA polymerase I levels in these tissues are regulated by similar physiological parameters.